Once a recreational vehicle has been parked, it is desirable to level the vehicle. Sensing devices are known in the prior art, including mercury switches, electrolytic liquids or accelerometers. These have been used in the prior art, with varying degrees of success, to attempt leveling. A problem with any of these sensors is that in order to make them sensitive enough to measure the tilt angle of a vehicle accurately, where the angle may be relatively small and still large enough to affect the performance of slide outs, etc, the sensors tend to be overly sensitive to the shock or bump imparted by the leveling actuators, especially when these actuators are, as they are conventionally, hydraulic or electric screw jacks. Regardless of the style of jack, the chance of actually being able to correctly determine the exact point at which a vehicle becomes level may be very difficult due to the impulses, such as impulses A, B and C in FIG. 1b, imparted on the sensing element.
The following is a description of how the accelerometers within accelerometer-type tilt sensing devices operate: The accelerometer in such a device is used to measure acceleration along one or more axis of sensitivity. Conventionally, accelerometers measure the acceleration of a body to which the accelerometer is attached. However, in a tilt sensor, the sensor is placed so that one of its measurement axes is substantially perpendicular to the pull of the earth's gravity. As the sensor is tilted so that the relationship between the sensor and gravity is no longer perpendicular, the amount of tilt is determined by measuring the amount of gravitational pull being measured. At a perpendicular state, the amount measured is zero. If the sensor were rotated to become parallel, the amount measured would be 1 G (or 32.17 ft/sec2). At any position in between, the tilt angle can be derived by the following formula.
  tilt_angle  ≡            sin              -        1              (          MeasuredValue              32.17        ⁢                                  ⁢                  ft                      sec            2                                )  
It is therefore an object of the present invention to provide a method of vehicle leveling that provides for very accurate leveling while compensating for the shock imparted into the vehicle and therefore measured by the sensing device.
It is another object of the present invention to provide a control system and method of leveling of the vehicle using either a two-axis sensor or multiple lateral and longitudinal tilt sensing axes.
It is another object of the present invention to provide a control system and method of leveling of the vehicle using three or four leveling jacks.
It is another object of the present invention to provide a control system and method for leveling a vehicle wherein each corner of the vehicle may be independently or cooperatively raised or lowered.
It is a further object of the present invention to provide a control system and method for leveling a vehicle wherein an operator may manually adjust the height of each individual corner or group of corners of the vehicle without exceeding a certain amount of chassis twist.